Drain valve mechanism for fluid pressure systems



A. W. HALL Dec. 15, 1953 DRAIN VALVE MECHANISM FOR FLUID PRESSURE SYSTEMFiled Feb. 11, 1950 5 4 6 5 V m m W H IV f\\\ u B. 1 1K 00 a a 4 m5 1INVENTOR AXE 1M HALL BY Hirer/1P) atented Dec. 15, 1953 UITED STATESPATENT OFFICE 2,662,544 DRAIN VALVE MECHANISM FOR FLUID PRESSURE SYSTEMSAxel W. Hall, Still- River, Mass. Application February 11, 1950, SerialNo. 143,790

4 Claims. (01. Lav -204) The present invention relates to fluid pressuresystems, particularly air pressure systems em ployed on moving vehicles,and has for its object to provide an improved valve mechanism forautomatically draining liquid, and other foreign matter, from thepressure storage reservoir of such a system.

In the normal operation of air pressure systems, such as those employedfor operating the air brakes and other auxiliary apparatus of motorbuses, trucks and other heavy vehicles, it has been found that liquid,mostly in the form of water, will collect within the system, due to thecondensation of moisture that is present in the air. When this water,which is often mixed with oil and sludge, is not drained, its presencewill interfere with the operation of the system, and. may render thesystem entirely inoperative, due to its freezing in cold weather. Whilemanually operated drain valves have been employed, it is difiicult toinsure the operation of such valves at regular intervals.

According to the present invention, there is provided a drain valvemechanism, which maybe readily applied to the reservoir of any existingair pressure system, with the valve mechanism functioning automaticallyto cause the periodic discharge of liquid from the system in response tovariations of pressure Within the reservoir. The

valve mechanism of the present invention is particularly characterizedby its simplicity of construction, its ready application to any pressurestorage reservoir, or other receptacle at a low point in the system, andthe fact that the mechanism operates automatically without the use ofsprings, or parts that are liable to get out of adjustment.

The above, and other advantageous features of the invention willhereinafter more fully appear from the following description whenconsidered in connection with the accompany drawings, in which,

Fig. 1 is a diagrammatic showing of an air pressure system to which myimproved drain valve mechanism has been applied.

Fig. 2 is a vertical sectional view, on an enlarged scale, or the valvemechanism shown in Fig, l in its closed position.

Fig. 3 is a sectional view, similar to Fig. 2, showing the valvemechanism in its open position.

Fig. 4 is a horizontal sectional view along the line e-e of Fig. 2,looking in the direction of the arrows.

Referrmg first to Fig. 1, the-fluid pressure system to which my valvemechanism V is applied, includes a storage reservoir 5 supplied with airunder pressure, through a conduit 2 leading from a suitable compressor3. The reservoir l functions to store air under pressure for use byvarious types of air operated apparatus, such as vehicle brakes, withthe air passing to such apparatus through a conduit 4%, leading from thereservoir 1.

As best shown on an enlarged scale in Fig. 2, the valve mechanism Vcomprises a cylindrical casing 5 substantially closed at its upper end,which provides an externally threaded nipple 6, screwed into a threadedopening 5 extending through a boss 8 formed on the bottom of thereservoir I. The opposite end of the casing 5 is open to receive a head9 in the form of a disc threaded or otherwise fitted into the end of thecasing, so as to form an air-tight closure for the casing when the partsof the valve have been as sembled therein.

The head 9 provides a centrally located port ill surrounded by a conicalseat H for receiving a valve 62 carried at the lower end of a stem :2.The valve stem it carries a piston M, which is shown as being in theform of a cup-shaped washer composed of yieldable material, such asrubber or leather, with the outer rim or flange E5 of the piston beingslightly larger than the inside of the casing s. It is to be noted thatthe edge of the flange i 5 faces in the direction of the valve it, sothat entry of the piston I 3 into the casing 5 will serve to slightlycompress the flange l5.

The central portion of the piston M is held between plates 6, the lowerone of which engages a shoulder l l provided by the stem It, and a nut48 serves to hold the plates is in close engagement with the flatsurface of the piston It by its cooperation with threads is formed on areduced portion 2a or" the stem 53 above the shoulder ll. Therefore,when the parts of the piston are assembled on the stem it, the centralportion of the piston 14 is relatively stiff, uith the flange [5surrounding this central portion being relatively flexible, for apurpose which will later appear.

The reduced portion 28 of the valve stem It extends freely into anopening 2! formed in the nipple 5. As best shown in Fig. the sides ofthe stem portion 22 are flattened at 22, so that air under pressurewithin the reservoir i will always be admitted freely to the upperportion or the casing 5, above th piston is, when the valve 06- cupiesthe closed position of Fig. 2. Thus, the

:upperportion 2% of the valve'stem it serves as a guide to keep thecentral axis of the stem l3 in alignment with the port It at the lowerend of the casing, with the rounded corners between the flattenedportions 22 sliding freely within the opening 2|.

When the parts of the valve mechanism are assembled within the casing 5,the stem I3 normally occupies the position of Fig. 2, with the port toclosed. Therefore, when the valve assembly is applied to the reservoirl, air under pressure enters the casing 5 through the opening '21, andthis pressure acting on the top of the piston i-l, serves to firmlypress the valve [2 in engagement with the seat ii surrounding the port.After the air in the reservoir 1 has been under pressur for anappreciable time, the pressure on opposite sides of the piston 14 willequalize, due to the fact that the piston flange i5, being yieldableinwardly to pressure exerted on its upper surface its edge and the innerwall of the casing 5. Furthermore, any condensed moisture collecting atthe bottom of the reservoir in the form of water mixed with oil, willflow downwardly through the opening 24 into the space above the piston il, and will ultimately seep with the air past the flexible flange oi thepiston it, as indicated in Fig. 2. This moisture will then collect atthe bottom of the casing 5 around the valve i2, which is then heldtightly in engagement with its seat H by the air pressure in thereservoir 1.

Assuming that the air pressure in the reservoir 5 is normally maintainedat 169 pounds per sq. in, the air pressure on opposite sides of thepiston it will also be 190 pounds. Therefore, as long as the pressureremains the same on both sides of the piston is, the valve ill will beheld in engagement with the seat ii surrounding the port Ill. However,should the air pressure in the reservoir i, fall below 100 pounds, dueto the use of the air for operating apparatus in the system, such asbrakes, then air above the piston i l will have its pressure reduced,say to 95 pounds, while air below the piston will remain at the originalpressure of mo pounds. as soon as this condition occurs, an u ward forcewill be exerted on the piston It by this residual air pressure below thepiston which is suiiicient to move the piston into the position of 3,wherein the valve !2 has been raised above its seat i i with upwardmovement of the piston it being limited by the nut it. This lifting ofthe valve immediately followed by is is discharge of the accumulatedmoisture through the port as indicated by the arrows.

As soon as this discharge of moisture through i the port it occurs, theaccompanying escape of air from below the piston I 3 into theatmosphere, will recuce the pressure to a value below the 95 pounds orpressure remaining in the space above the piston, whereupon the valvestem is will again move downwardly into the position of Fig. 2 to closethe port of the valve l2. Such valve closure will be followed by theabove described seepage of air under pressure and moisture into thespace below the piston i i, as equalization of pressure again takesplace, as before, whereupon the cycle of operation of the valvemechanism will repeat itself, upon the occurrence of a further reductionin the pressure within the reservoir i, such as from 95 pounds to 90pounds. The values of air pressure stated above are given for purposesof illustration only, it being obvious that the initial equalization ofpressures on opposite sides or the piston will occur at any givenpressure that is normally maintained in the will allow the air to seepbetween system, and that any substantial reduction 0! this normalpressure will result in automatic opening of the valve 12, due to theexistence of a residual pressure below the piston M in excess ofwhatever pressure may then be above the piston, due to its directcommunication with the reservoir I.

From the foregoing, it is apparent that by the present invention, thereis provided an improved valve mechanism that operates to clear thesystem of accumulated moisture, at frequent intervals, automaticallydetermined by variations of pressure within the system resulting fromthe normal use of the pressure median in operating various types ofapparatus. While for purposes of illustration, the valv mechanism isshown as being applied to a pressure storage reservoir, obviously itwould function just as effectively when applied to a drainage receptaclelocated at a low point in the system, where it will be subjected to thepressure of the system.

I claim:

1. A drain valve device for a fluid pressure system comprising incombination, a casing providing a smooth-wall cylinder having an openingin its upper end and having its lower end provided with a dischargeport, a piston movable within said cylinder and carrying a valve portionresponsive to downward movement of said piston to close said dischargeport, said piston having a portion or flexible material around itsperiphery with a flange facing in the direction of said discharge portso as to yield inwardly in response to pressure in the upper portion ofsaid cylinder to permit the passage of fluid and moisture to the lowerportion of said cylinder when piston moves downwardly to cause saidvalve portion to close said discharge port,

ccompanied by equalization of pressure on opposite sides of said piston,and with the peripheral portion or said piston yielding outwardly toprevent passag of fluid and moisture from the lower to the upper portionof said cylinder in response to a decrease of system pressure below thepressure in the lower portion of said cylinder, accompanied by upwardmovement of said piston to disengage its valve portion from said portfor discharging through it fluid and moisture from the lower portion ofsaid cylinder to the atmosph re, until pressures on the opposite sidesof said piston are again equalized.

A drain valve device for a fluid pressure reservoir comprising incombination, a cylinder having an opening in its upper end providing apassage extending into said cylinder, said cylinder being closed at itslower end, except for an exhaust port, and a piston assembly movablewithin said cylinder comprising a rod extending axially thereof, withthe lower end of said rod providing a valve portion engageable with saiddischarge port and the upper end of said rod being guided for movementin said passage, and with the inter- -mediate portion of said rodcarrying a ri id portion of less diameter than the bore of said cylinderand a second portion of flexible material having a diameter greater thanthat of said cylinder bore, so that when said piston assembly is placedwithin the cylinder said flexible portion will be compressed to providea flange engaging the cyiinder wall and yieldable inwardly to allowpassage of fluid and moisture from said reservoir while permittingdownward movement of said piston to close said discharge port by saidvalve portion.

3. A drain valve device for a fluid pressure reservoir comprising incombination, a cylinder having an opening in its upper end providing apassage extending into said cylinder, said cylinder being closed at itslower end, except for an exhaust port, and a piston assembly movablewithin said cylinder comprising a rod extending axially thereof, withthe lower end of said rod providing a valve portion engageable with saiddischarge port and the upper end of said rod being guided for movementin said passage, and with the intermediate portion of said rod providinga shoulder on which is mounted a pair of rigid discs of less diameterthan the cylinder bore, and a disc of flexible material held betweensaid rigid discs, said flexible disc being of greater diameter than thecylinder bore so that when said piston assembly is placed within saidcylinder the peripheral portion of said disc will flex inwardly in thedirection of said valve portion to yieldingly engage the cylinder wallpassage of fluid and moisture beyond said piston.

4. A drain valve device for a reservoir containing a fluid pressuremedium comprising in combination, a cylinder having one end providedwith a passage and having its other end provided with an openingsurrounded by a seat, a rod extendand permit the ing axially of thecylinder with one end guided for movement within said cylinder passageand having its other end provided with a valve portion engageable withsaid seat, and a piston mounted on said rod between the ends thereof,said piston comprising a rigid portion of less diameter than the bore ofsaid cylinder and a second portion of flexible material of greaterdiameter than said cylinder bore, whereby the placing of said rod andpiston within the cylinder will serve to flex the periphery of saidflexible piston portion in the direction of said valve portion toyieldingly and slidably engage the cylinder wall and permit the passageof pressure medium and moisture from beyond said piston when movement ofthe piston has engaged said valve portion with said seat.

AXEL W. HALL.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,125,144 Aikman July 26, 1938 2,232,899 Aikman Feb. 25, 19412,233,818 Matter Mar. 4, 1941

